Production of iso-octane



PRODUCTION OF ISO-QCTANE Original Filed Jan. 18, 1940! l NORMAL & ISO-BUTANES N BUTANE' FRACTION r DEHYDRO- cam-non .ZONE

1 i 1 lSO-BUTANE I 53% v I UNCONVERTED zi zag-T8 SEPARATION FRACTION lSO-BUTANE FROM DEHYD- FRACTION {HYDROGEN ROGENATION I8 BUTANE-4' H I BUTENE v FRACTION ,4 (CHARGE) 0 ISO-BUTENE FRACTION- ZONE RESIDUAL BUTANE- 2| POLYMERI- @UTENE ZATION 1 FRACTION ZONE ' RESIDUAL 24 26 BUTANE YMER FRACTION HEAVY 3 POLYMERS HYDROGEN- ATION 39 ZONE RESIDUAL HYDROGENATED UNUSED 38 37 c POLYMERS HYDROGEN INVENTOR LOUIS s. KASSEL BY i ATTORNEY Patented Mar. 10, 1942 PRODUCTION OF ISO-OCTANE Louis s. Kassel, Chicago, n1., mi or to Universal 011 Products Company, Chicago, Ill.,la corporation Delaware Continuation of application Serial No. 314,484,

January 18, 1940. This application November- 22, 1940, Serial No. 366,734

11 Claims.

This invention relates to a process for the manufacture of iso-octane from butanes and more specifically it is concerned with a process involving a series ofindividual steps combined in a novel and advantageous manner so that they cooperate to produce optimum results in the conversion of butanes to iso-octane. This applica-' tion is'a continuation of my earlier application Serial No. 314,484, filed January 18, 1940.

' aviation gasoline has materially improved. De-

hydrogenation, however, is an expensive operation and can only be justified when substantially all of the olefins formed are utilized but more particularly when they are polymerized to normally liquid polymers which upon hydrogenation yield a product having a relatively high 0c,- tane rating making it valuable as an aviation gasoline. a

In the polymerization of butenes wherein the proportion of normal butenes to iso-butene in the fraction is ordinarily high, the ratio sometimes exceeding 3:1, it is possible under selected conditions to substantially completely polymerize the. isobutene and. obtain a very satisfactory amount-of cross-polymerization between the iso and normal butenes. However, since in the ordinary charging material formed as aproduct in a cracking operation or in the dehydrogenation of a butane fraction, the normal butenes exceed or are produced considerably in excess of isobutene, a substantial proportion of the normal butenes even under optimum conditions remain unconverted. Substantially complete removal of normal butenes may be obtained ina subsequent polymerization step under more drastic conditions, however, the polymers obtained in this latter step have a relatively poor octane rating In addition to those reasons stated above for the desirability of substantially completely regases after polymerization, ,others also suggest moving the normal butenes from the residual themselves, the most obvious of which is that it is undesirable to return butenes in any form to the dehydrogenation zone because the amount of conversionto oleflns which may be efiected is materially decreased as equilibrium between the butenes and butanes is partially reached before any dehydrogenation is eflected. In addition, when butenes are recycled to the dehydrogenation treatment, it is also possible that the production of di-olefins may be increased, and since they break down more readily the carbon deposition may also increase.

One obvious method of avoiding the production of excess quantities of normal butenes by dehydrogenation of butanes would involve separation of iso-butane from the normal butane and dehydrogenation of the former to iso-butene. This method, however, would restrict the production of iso-octane substantially to the available iso-butane with only a small proportion of .normal butane being used. This process, therefore, would not be particularly valuable, since relatively large amounts of normal butane exist and a relatively large proportion thereof would re-.

main unused.

My invention obviates the necessity of a separate normal butene polymerization step and proupon hydrogenation as compared to iso-octane produced by the cross-polymerization of normal and iso-butenes or by the polymerization of isobutene only followed in each case by hydrogenation. Since the normal butene polymer has a relatively low octane rating after hydrogenation and since its value is small as compared to the standard iso-octane, the expense at which normal butene is produced in dehydrogenation cannotbe justiiied' in a process which provides for the straight polymerization of normal butene in a secondary, polymerization treatment.

v'ides for polymerizing a substantial portion of the normal butenes available under conditions which give a high ratio of normal butenes removed to iso-butene and in addition provides for substantially complete removal of normal butenes by polymerizing them in the presence of an excess of iso-butene, thereby converting substantially all of the butenes .formed' in the process and introduced thereto to iso-octenes which are converted ,to iso-octane upon hydrogenation.

To accomplish the object of my invention, I I propose to separate the charging stock containing the normal and iso-butanes into two portions, one portion of which is subjected to fractionation to separate the normal butane from the isobutane whereupon the iso-butane is subjected to dehydrogenation treatment and the normal butane recovered for blending ingasolines to raise its vapor pressure or for any other desired purpose, and the second portion of which issubjected to separate dehydrogenationtreatment. Preferably also the separation into the two portions is controlled so that the portion-subjected to fractionation contains a quantity of normal Reference is now made to the flow diagram. Charging stock comprising normal and isobutanes is introduced through line I and is passed into line 2 where the charge is separated into two portions, one portion being introduced to separation zone 3 and the other portion todehydrogenation zone 4. Preferably, also, the porcharging stock contains iso and normal butane in the mol ratio of 3:7 before dehydrogenation, on the basis of 100% conversion of butanes to butenes in dehydrogenation and on the basis that 1 mol of n-butene may be polymerized per mol of iso-butene, the object would be to fractionate that portion of the charge containing the excess of n-butane or 40 mol with the corresponding amount of iso-butane; Therefore, in the case of the example stated above on a 100 mol basis, the portion subjected to fractionation treatment would contain 40 mols of normal butane and approximately 1? mols of iso-butane or, in other words, the charging stock is separated into a fraction containing approximately 57 mols of the charging stock and one containing approximately 43 mols.

In one specific embodiment the invention comprises separating the charging stock consisting essentially -'of normal and iso-butanes into two portions, subjecting one portion to fractionation to separate the normal'from the iso-butanes and recovering the normal butane fraction, subjecting the iso-butane fraction to dehydrogenation treatment, substantially separating the products,

recycling the unconverted iso-butane and recovtion introduced to separation zone 3 corresponds to that portion of the charging stock which contains an amount of normal butane in excess ofthe quantity which, if converted to normal butenes, could advantageously be utilized in the system; i. e., it corresponds to the amount of normal butane which, if all the butanes introduced to the system were converted to butenes, would remain unpolymerized after the subsequent polymerization treatmentsi In separation zone-3 the iso and normal butanes are separated from each other and the normal butane fraction removed by way of line 5 and recovered as a product of the process for use in blending with distillates to meet a vapor pressure requirements or for any other desired purpose. It is also within the scope of the invention, however, to commingle all or a portion of the normal butane fraction in line 5 with the other portion of the charging stock subjected to dehydrogenation treatment in zone 4 by directing it through line 6 into line 2, in which case unconverted butanes separated after the polymerization treatments would be withdrawn from the process in order to avoid a buildup of normal butanes inthe system. The first procedure, however, is preferred over the latter, in

I former with the hydrogen from the first mentioned dehydrogenation treatment for use as hereinafter set forth, subjecting said butanebutene fraction to polymerization treatment and introducing at least a portion of the iso-butene formed in the first mentioned'dehydrogenation treatment at intermediate points in said Polymerization treatment whereby to effect the desired cross-polymerization between the normal and iso-butenes, separating the residual butanebutene fraction from the polymers formed in said polymerization treatment, commingling the former with the residual portion of the iso-butene and subjecting the mixture to a separate polymerization treatment under conditions selected to effect substantially complete removal of the olefins contained in the mixture, separating the residual butane fraction from the polymers formed in said separate polymerization treatment The accompanying diagrammatic drawing il-'- lustrates the principal steps of the process, the drawing being'in the form of a flow diagram in order to avoid complicating it with unnecessary details.

view of the fact-that the unconverted butane separated as hereinafter described after the polymerization treatment contains also iso-butane which is the more desirable component.

The iso-butane fraction separated in zone 3. is directed through line I and commingled with the unconverted isobutane fraction separated as hereinafter described, and the mixture subjected to dehydrogenation treatment in zone 8. Dehydrogenation in zone 8 may be accomplished in any of the well known forms of apparatus in the presence of catalysts having a selective action in promoting the dehydrogenation reaction. Prod nets of the dehydrogenation treatment in zone 8 consisting essentially of unconverted iso-butane, iso-butene, and hydrogen'are directed through line 9 to separation zone l0 where the unconverted iso-butane is separated from the isobutene and hydrogen and the former returned as recycle to the dehydrogenation treatment by way of line H Hydrogen separated in zone In from the iso-butane and iso-butene is removed by way of line I2 and commingled in line IS with hydrogen formed as hereinafterdescribed, the mixture being used in a subsequent hydrogenation treatment. The iso-butene fraction separated in zone I0 is removed by way of lin l3 and is utilized in the manner to be described later.

The residual portion of the charging stock not introduced 'to separation zone 3 is commingled,

when desired, with the residual unconverted butane fraction separated as hereinafter de--- scribed, and the mixture subjected to dehydrogenation'treatment in zone 4. Here again dehydrogenation may be accomplished in any of the wellknown forms of apparatus and in the presence of catalytic materials capable of promoting the desired reaction. The productsof the dehydrogenation treatment in zone 4 consisting essentially of butanes, butenes, and hydrogen are directed through line I! .to separation I is removed therefrom by way of line l1 and, when desired, commingled with the butane-butene fraction introduced from an outside source by way of line l8 and the mixture subjected to polymerization treatment in zone I3. When a butane-butene fraction is introduced to zone l9 from an outside source, it is also within the scope of the invention to provide for the removal of normal butane in separation zone 3 equivalent to the amount of normal butane present in the butane-butene fraction in order to avoid an increase in concentration of normal butane in the residual unconverted butane which is returned to dehydrogenation zone a inthe manner to be described later..

Polymerization treatment in zone is is preferably carried out in at least two stages and preferably also in the presence of a 'suitable polymerizing catalyst such as, for example, sulfuric acid or the solid phosphoric acid-containing catalyst. The multiple stage polymerization treatment in zone l9 isadvantageous from the standpoint of flexibility, for with this procedure it is possible to provide for the introductionof iso-.butene between the various stages whereby-the optimum ratio of iso-butene to normal butene may be maintained in each stage. Iso-butene for this purpose may be supplied from separation zone ill by way of line l3 and line and introduced in lighter polymers comprising essentially iso-octenes are directed through line 33 to hydrogena tion treatment in zone 3| which is preferably accomplished in the presence of a nickel-containing catalyst, while introducing hydrogen by way of line 16 separated from the dehydrogenated products as previously described.

The products of the hydrogenation treatment in zone 34 are directed through line 35 to separation zone 36 where the residual unused hydrogen is separated from the hydrogenated polymers and the latter recovered as a productof the process by way of line 31. Residual unused hydrogen is removed from separation zone 36 by "way of line 38 and recovered or, when desired, returned to hydrogenation treatmentin zone 34 by way of line 39.

The following are the results which may be obtainedfrom a process conducted in accordance with the invention as above described. It is merely one specific example and it is not to be considered a limiting feature, for results may vary depending upon the catalyst and conditions employed and charging stock composition.

In this example the charging stock consists of r a butane fraction containing approximately 700 Y butane and 120 mols oi iso-butane. The first porsuch quantities so as to maintain the desired ratio of iso to normal butane.-

The polymerization products from zone l9 are directed through line 2| into separation zone 22 wherein the residual butane-butene fraction is separated from the normally liquid polymers and acid catalyst or other catalysts such as the phos- Polymerization treatment in zone 25 may be accomplished using a sulfuric tion having'the higher normal butane content is subjected to fractionation to separate an iso- .butane fraction from the normal .butane fraction,

the former containing approximately 1'70 mols of iso-butane and 10 mols. of normal butane being subjected to further treatment andthe latter containing 410 mols of normal butan and 10 mols phoricacid-containing catalyst, and since the iso-butene is the predominating olefin in the mixture, conditions may very readily be selected to effect the desired cross-polymerization.

The products of the polymerization treatment in zone 25 are directed through line 26 to separation zone 27. wherein the residual butane fraction V is separatedfrom the normally liquid polymers and the former removed by way oflinejfl and re-. cycled to the dehydrogenation treatment in zone 4 for treatment as previously described, or, when desired, recovered as a product of the process by way of line 29. The normally liquid polymers.

separated inzone 21 are removed therefrom by way of line 30 and commingled with the normally liquid poLvmers in line 23 and the mixture intro- -duced to separation zone 3! wherein by means of fractionation the heavy liquid polymers, preferably comprising those containing more than 8 chromic oxide.

of iso-butane. is recovered as a product of a process.

The iso-butanefraction totaling 180 molsof both normal and iso-butane is subjected to dehydrogenation treatment in the presence of an alumina-chromia catalyst at a. temperature at r 1000 F. and at a pressure of approximately 20 pounds per square inch. The catalyst may be prepared by the precipitation of alumina as a hydrogel, the h'ydrogel dried and pelleted and the pellets impregnated with chromic acid, after which they are dried and calcined to form a catalytic material containing aluminumoxide and The ultimate recycle products from the isobutane dehydrogenation treatment containing approximatel 144 mols of iso-butane condensation and the hydrogen separated and.

- recovered.

carbon atoms'to the molecule. are separated from The residual portion of the charging material containing approximately 280 mols of normal butane and mols of iso-butane is subjected to a separate dehydrogenation treatment in the presence of a catalytic material of substantially the same composition as that previously described under substantially the same conditions of temperature and pressure. Neglecting the unconverted butanes leaving the last mentioned dehy- .drogenation treatment for recycle operation is -employed,' the material leaving the last mentioned dehydrogenation zone contains approxiand condensation and commingled'with the hy.

. purpose.

drogen formed in the first mentioned dehydrogenation treatment for use as hereinafter deand second stage of this step approximately 64 mols of iso-buten are added, thismaterlal having been formed in the iso-butane dehydrogenation treatment. The product from the second step contains approximately 67 mols of iso-butene and 75 mols of normal butene as normally liquid polymers, 2 mols of viso-butene and 2 mols of normal butene, together with the unconverted butanes.

Th'e residual butane-buten fraction is separated from the normally liquid polymers following the polymerization treatment, the former commingled with the iso-butene fraction formed as previously described, and the mixture subjected to polymerization treatment in the presence of a phosphoric acid-containing catalyst at a temperature of 225 F. and at a pressure of 1000 pounds -per square inch. Products from this treatment comprising essentially normally liquid polymers and unconverted butanes are separated and the latter returned to the second mentioned dehydrogenation treatment. The normally liquid polymers formed in the last mentioned polymerization treatment are commingled with those from the first mentioned polymerization treatment and the mixture fractionated to separate heavy polythe dehydrogenation treatment, concurrently therewith subjecting the other portion of said normal and isobutane mixture to a separate dehydrogenation treatment to effect substantial dehydrogenation to butenes and hydrogen, separating and commingling the hydrogen formed in both dehydrogenation treatments for use as hereinafter set forth, subjecting the products from the second mentioned dehydrogenation treatment after separation of hydrogen to polymerization treatment under conditions selected to eiIect substantial polymerization to iso-octenes,

commingling the residual unconverted gases from said polymerization treatment with the isobutane fraction formed in the first mentioned dehydrogenation treatment and subjecting the mixture to a separate polymerization treatment to polymerize a substantial portion of the remaining butenes, separating the unconverted gases from mers from the lighter normally liquid polymers and the latter hydrogenated in the presence of a nickel-containing catalyst at a temperature of 275 F. and at a pressure of 100 pounds per square inch. The heavy polymers corresponding to approximately 5.9 mol per cent of the charging stock and iso-octane corresponding to approximately 43.4 mol per cent of the original charging stock are recovered as products of the process.

which could be used for blending in gasolines to raise its vapor pressure or for any other desired The loss from the process usually amounts to about 8.8 mol per cent of the charging stock.

I claim as my invention: l 1. In a process for the production of isq-octane wherein normal and isobutanes present in the ,charge are subjected to dehydrogenation ,treatment to convert the butanes to butenes and the butenes subsequently polymerized-to form isooctenes which are hydrogenated to iso-octane, the improvement which comprises separating the normal and isobutane mixture into two portions, fractionating one portion to separate an isobu-.

tane fraction from the normal butane fraction and recovering .the. latter, subjecting said isobutane fraction to dehydrogenation treatment to eiIect substantial conversion to isobutene, substantially separating isobutane from the isobutne and hydrogen and returning the former to the normally liquid polymers formed in the lastnamed polymerization treatment and returning the former to the second-mentioned dehydrogenation treatment, commingling the polymers from both polymerization treatments and subjecting the mixture to hydrogenation treatment using hydrogen separated as previously set forth and recovering therefrom a hydrogenated polymer.

2. In a process for the production'of iso-octane from charging stock containing essentially normal and isobutanes wherein said charging stock is subjected'to dehydrogenation treatment to convert the butanes to butenes and the butenes substantially polymerized to form iso-octenes which are hydrogenated to iso-octane, the improvement which comprises separating said charging stock into two portions, fractionating one portion to separate an isobutane fraction from the normal butane fraction and recovering the latter, subjecting said isobutane fraction to dehydrogenation treatment to effect substantial conversion to isobutene, substantially separating isobutane from the isobutene and hydrogen and retuming the former to the dehydrogenation treatment,

concurrently therewith subjecting the other portion of said charging stock to a separate dehydrogenation treatment to eflfect substantial dehydrogenation to butenes and hydrogen, separating and commingling the hydrogen formed in both dehydrogenation treatments for use as hereinafter set forth, subjecting the products from the second mentioned dehydrogenation treatment after separation of hydrogen to polymerization treatment under conditions selected to effect subseparating the unconverted gases from the nor- 'mally liquid polymers formed in the last-named polymerization treatment and returning the former to the second-mentioned dehydrogenation treatment, commingling the polymers .ir'om-both from chargingstockcontaining essentially normal and isobutanes wherein said charging stock is subjected to dehydrogenation treatment to convert the butanes to butenes and the butenes poly- 2,276,199 merized to form iso-octenes which are hydro-' genated to iso-octane, the improvement which comprises separating said charging stock into two portions, one portion containing the normal b u,

tane present in the charge in excess of the quantity which may be advantageously utilized in the process, together with the proportionate quantity of iso-butane, while the other portion is equivalent to the remaining charging material, fractionating the first named portion to separate an iso-butane fraction from the normal butane fraction and recovering the latter, subjecting said isobutane fraction to dehydrogenation treatment to efiect substantial conversion to isobutene, substantially separating isobutane from the isobutene and hydrogen and returning the former to the dehydrogenation treatment, concurrently therewith subjecting the second named portion of said charging stock to a separate dehydrogenation treatment toeffect substantial dehydrogenation to butenes and hydrogen, separating and commingiing the hydrogen formed in both dehydrogenation treatments for use as hereinafter set forth, subjecting the products from the second mentioned dehydrogenation treatment after separation of hydrogen to polymerization treat-= ment under conditions selected to effect substantial polymerization to iso-octenes, commingling the residual unconverted gases from said polymerization treatment with'the isobutene fraction formed in the first mentioned dehydrogenation arated-as previously set forth and recovering therefrom a hydrogenated polymer. I

4. In a process for the production of iso-octane from charging stock containing essentially normal and iso-butanes wherein said charging stockis subjected to dehydrogenation treatment to convertthe butanes to butenes and the butenes polymerized to formiso-octenes which are hydrogenated to iso-octane, the improvement which comprises separating said charging stock into two portions, one portion containing the normal butane present in the charge in excess of the quantity which may beadvantageously utilized in the process, together with the proportionate quantity of isobutane, while the other portion is equivalent to the remaining charging material, fractionating the first named portion to separate an iso-butane fraction from the nor-' malbutane fraction and recovering thalatter, subjecting said isobutane fraction to dehydrogenation treatment to efiect substantial conver-' sion to isobutene, substantially separating isodual unconverted gases from said polymerization treatment with the residual portion of said isobutene fraction and subjecting the mixture to a separate polymerization treatment to polymerize a substantial portion of the remaining butenes separating the unconverted gases from the normally liquid polymers formed in the last named polymerization treatment and subjecting the former to further dehydrogenation treatment in commingled state with the second named portion of said charging stock, commine gling the polymers from both polymerization treatments and subjecting the mixture to hydrogenation treatment using hydrogen separated as previously set forth and recovering therefrom a hydrogenated polymer.

5. In a process for the production of iso-octane from charging stock containing essentially normal and isobutanes wherein said charging stock is subjected to dehydrogenation treatment to convert the butanes to butenes and the butenes polymerized to form iso-octenes which are hydrogenated to iso-octane, the improvement which comprises separating said charging stock into two portions, one portion containing the normal butane present in .the charge in excess of the quantity which may be advantageously utilized in the process together with the proportionate quantity of isobutane, while the other portion is equivalent to the remaining charging material, fractionating the first named portion to separate an isobutane fraction from the normal butane fraction and recovering the latter,

subjecting said isobutane fraction to dehydrogenation treatment to eilfect substantial conversion to isobutene, substantially separating isobutane from the isobutene and hydrogen and returning the former to the dehydrogenation butane from the isobutene and hydrogenand returning the former to the'dehydrogenation treat-. ment, concurrently therewith subjecting the second named portion of said charging stock to a separate dehydrogenation treatment, subjecting,

the products from the second named dehydrogenation treatment after separation'of. hydrogen to polymerization treatment under conditions selected to eifect substantial polymerization to iso-octenes. and while introducing a portion of the isobutene formed in the first jmentio'neddehydrogenation treatment, commingling the resitreatment, concurrently therewith subjecting the second named portion of said charging stock to a separate dehydrogenation treatment, subjecting the products from the second named dehydrogenation treatment after separation of hydrogen to polymerization treatment under conditions selected to effect substantial polymerization to iso-octenes and while introducing a portion of the isobutene formed in the first mentioned dehydrogenation treatment, commingling the residual unconverted gases from said I polymerization treatment with the residual portion of said isobutene fraction and subjecting the mixture to a separate polymerization treatment to polymerize a substantial portion of the remaining butenes, separating the unconverted gases from the normally liquid polymers formed in the last named polymerization treatment and subjecting the former to further dehydrogenation treatment in, commingled state withthe second named portion of said charging stock, oommingling the polymers from both polymerization treatments and fractlonating the mixture to separate the light fronr'the heavy polymers, recovering the. latter, and subjecting, the light polymers'tohydrogenation treatment using hydrogen separated as previously set forth-and recovering therefrom iso-octane.

6. In a process forthe production of isooctane from charging stock containing essentially normal and iso-butanes wherein said charging stock is subjected to dehydrogenation treatment to convert the butanes to butenes and the butenes polymerized to form iso-octenes containing the normal butane present in the charge in excess of the quantity which may be advantageously utilized in the process together with the proportionate quantity of isobutane, while the other portion is equivalent to the remaining charging material, fractionating the comprises separating a substantial portion of isobutane from the charging" stock, subjecting it to dehydrogenation to produce iso-butylene, separately dehydrogenating the remainder of said charging stock, adding a portion of said isobutylene to the reaction products from the latter first named portion to separate an isobutane fraction from the normal butane fraction and recovering the latter, subjecting said iso-butane fraction to dehydrogenation treatment to eflect substantial conversion to isobutene, substantially separating isobutane from the isobutene and hydrogen and returning the former to the dehydrogenation treatment, concurrently therewith subjecting the second named portion of said charging stock to aseparate dehydrogenation treatment, subjecting the products from the sec- 1 nd named dehydrogenation treatment after separation of hydrogen, together with a butanebutene fraction introduced from an outside source to polymerization treatment under conditions selected to effect substantial polymeriza- I tion to iso-octenes and while introducing a portion of the isobutene formed'in the first mentioned dehydrogenation treatment, commingling the residual unconverted gases from said polymeriz'ation treatment with the residual portion of said isobutene fraction and subjecting the commingling the polymers from both polymerization treatments and fractlonating the mixture to separate the light from the heavy polymers, recovering the latter and subjecting the light polymers to hydrogenation treatment using hydrogen separated as previously set forth and recovering therefrom iso-octane.

'7. Ina process for converting a charging stock comprising essentially normal and iso-butanes into high antiknock motor blending fuel comprising iso-octane, wherein said stock is subjected to dehydrogenation treatmentto convert butanes to butylenes, which are then polymerized to liquid polymer, which is in turn hydrogenated to produce substantiallysaturated motor blending fuel, the improvement which comprises separating at least a part of the iso-butane from the charge, subjecting it to dehydrogenation treatment to produce iso-butylene, concu'rrently subjecting the remaining portion of said charge step, subjecting the mixture to a polymerization step to produce liquid polymer, combining the unconverted'butylenes from said step with the remainder of said iso-butylene, subjecting the mixture to a polymerization treatment, recovering the iso-octylene polymers from both of the polymerization steps, and hydrogenating them to lso-octanes with the hydrogen produced in the aforesaid dehydrogenation steps.

9. In a process for the production of iso-octane wherein normal and iso-butanes present in the charge are subjected to dehydration treatment to convert the butanes to butylenes. and the butylenes subsequently polymerized to form isooctylenes which are hydrogenated to iso-octane, the improvement which comprises separating at least a portion of the iso-butane from the charge, subjecting it to dehydrogenation treatment-to produce iso-butylene, concurrently subjecting the remaining portion of said charge to a separate dehydrogenation treatment to produce a mixture containing butylenes, enriching the mixture with a portion of said iso-butylene, subjecting the mixture to polymerization treatment to produce polymer, separating gas containing unconverted butylene from the polymerization treatment, mixing it with the remaining iso-butylene produced in the first mentioned dehydrogenation step, subjecting the mixture to a second polymerization treatment to produce liquid polymers,

recovering an iso-octylene fraction from' the liquid products of, the aforesaid polymerization to a separate dehydrogenation treatment to pro duce a mixture containing butylenes, enriching said mixture with a portion of said iso-butylene;,

subjecting same to polymerization treatment to produce liquid polymer, combining'the unconverted butylenes from the polymerization treatment with the remainder of said iso-butylene, subjecting the mixture to a second polymerization treatment, recovering the liquid-polymers drogenated to iso-octane, the improvement which tially normal and'iso-butanes wherein/[said stock hydrogenation steps.

11. In a process for the-production of isothe hydrogen produced in said dehydrogenation steps to produce substantially iso-octane.

10." In a process for the production of isooctane from charging stock containing essentially normal and iso-butanes wherein said stock is subjected to dehydrogenation treatment to convert butanes to butylenes and the butylenes polymerized to iso-octylenos which are hydroenated to iso-octane, the improvement which comprises separating a substantial portion of isobutane from the butane charging stock, subjecting it to catalytic dehydrogenation treatment to produce iso-butylene, separately subjecting the remainder of said charging stock to catalytic dehydrogenation treatment to produce a mixture of butylenes, adding a portion of said iso-butylene to the mixture of butylenes produced in the last mentioned dehydrogenation step, subjecting the mixture-to polymerization treatment to produce liquid polymer comprising essentially isooctylenes, combining the unconverted butylenes from the polymerization step with the remailger of said iso-butylene from the first mentioned'dehydrogenation step, subjecting the mixture to polymerization treatment to produce liquid polymer, recovering the fraction 01' said liquid polymer comprising iso-octylene produced. in both polymerization steps, and hydrogenating said fraction with the hydrogen produced in said deoctane from;cha'rging stock containing essenis subjected to dehydrogenation treatment-to convert butanes to butylenes and the butylenes polymerized to form iso-octylene s, which 'are hydrogenated to iso-octane, the improvement which comprises separating at least-a portion '0! said iso-butane, subjecting it to catalytic dehydrog'enation treatment to produce iso-butylene, separating said iso-butylene for treatment as hereinafter indicated, separately subjecting the remainder of said charging stock to catalytic dehydrogenation to produce a mixture of butylenes, mixing therewith a portion of said iso-butylene, subjecting the mixture to catalytic polymerization to produce liquid polymers, combining the gases containing unconverted butylene from the polymerization treatment with the, remaining iso-butylene produced in the first mentioned dehydrogenation step, subjecting the mixture to catalytic polymerization to produce liquid polymers, separating a gaseous fraction comprising essentially butanes, returning said fraction to the last mentioned dehydrogenation step, recovering a fraction of polymers from both polymerization steps comprising essentially. iso-octylenes, and hydrogenating it with the hydrogen produced in the aforesaid dehydrogenation steps to produce iso-octane.

- LOUIS S. KASSEL. 

